Abstract: While the mapping from a distal stimulus to a retinal image is generally many-to-one, non-accidental properties in the image can point to a unique distal structure (Witkin and Tannenbaum, 1983) . The disproportionate degree of information carried by these properties suggests that the visual system might be particularly attuned to detecting and representing them when they appear in an image. Using a change detection task we investigated people's ability to detect a change to a scene when it involved a non-accidental property as compared with a change that didn't, theorizing that changes to properties that are ‘important’ to the visual system would be detected more efficiently. Our stimuli were highly simple ‘scenes’ consisting of a few (generally two) oriented line segments. In each trial, a configuration of the lines would appear for a brief time , replaced by a mask, and then a second configuration (either identical or with some change) would appear; observers had to respond based on whether they had seen a change or not (2-way, forced choice). The types of changes that could take place were the same for all trials, either a rotation or translation, generally of only one of the lines; the critical manipulation was where the change resulted in either the introduction or elimination of a non-accidental property (e.g. a configuration of collinear lines followed by one where one of the lines is slightly rotated). We found that a number of non-accidental properties led to much greater sensitivities then changes of equal magnitude (or greater) that did not involve one of these properties, suggesting a critical role for these properties in the visual representation.

Citation: WitkinA.TenenbaumJ.M.(1983). On the role of structure in vision. In Human and Machine Vision, RosenfeldA. ed. Academic Press.